Revolutionary organic solar cell design unleashes power of excitons

Researchers working with solar cells have devised a new material that could lead to the harnessing of substantially more renewable energy.

Solar energy is fast becoming the cheapest means of electricity production, but researchers from Columbia University have developed a new way to harness even more power and increase the efficiency of solar cells.

In a paper published to Nature Chemistry, the researchers described the design of organic molecules that are able to generate two excitons per photon of light through a process called singlet fission. These excitons are produced rapidly and can live for much longer than those generated from their inorganic counterparts, which leads to an amplification of electricity generated per photon that is absorbed by a solar cell.

Current solar panels all operate by the same process: one photon of light generates one exciton that can be converted into electrical current. Of course, two excitons is better than one, but so far researchers have struggled with the fact two excitons live no more than a few nanoseconds, making them difficult to harvest.

To keep these excitons around for longer, the Columbia researchers helped create the right organic molecules that can not only be used in next-generation solar energy production, but also in photocatalytic processes in chemistry, sensors and imaging. This is because they can be used to initiate chemical reactions used by industry to make pharmaceuticals and other types of consumer chemicals.

“This work is the first to show that singlet fission can rapidly generate two excitons that can live for a very long time,” said Luis Campos, one of the principal investigators of the study.

“This opens the door to fundamentally study how these excitons behave as they sit on individual molecules, and also to understand how they can be efficiently put to work in devices that benefit from light-amplified signals.”

He added that the design strategy implemented in this research could also prove useful to other scientific areas, but also a number of other applications that haven’t even been thought of yet.